Residential alarms (hereinbelow referred to as “alarm devices”) that emit an alarm upon detecting an anomaly such as a fire, gas leak or the like have become prevalent, and in recent years, there has been an increasing trend to perform monitoring for anomalies such as fires in every room by installing a plurality of alarm devices in a single residence (for example, refer to Patent Document 1).
In this way, when a plurality of alarm devices have been installed in a residence, in the case of a person being present in a separate room from the room in which an anomaly has occurred, there is the risk of the alarm sound not being audible to that person. For that reason, one has been proposed in which a linked alarm is possible by connecting alarm devices with wires, and so in the case of one alarm device having detected a fire and emitting an alarm, it is possible to transmit an alarm signal from that alarm device to the other alarm devices to cause them to sound simultaneously.
However, since wiring work is required in order to connect the alarm devices with wires, the problem arises of higher cost. The problem can be solved by adopting wireless alarm devices. Moreover, due to the reduced power consumption of wireless integrated circuits, even if placed in an operating state of being capable of always receiving a signal in order to be capable of receiving an alarm signal from another alarm device, a battery life that can withstand practical usage of over, for example, five years, is ensured. Therefore, the environment for making wireless alarm devices commercially viable is being put into place.
In such a wireless alarm device, since it is not known when a signal indicating an anomaly will be transmitted from another alarm device, it is necessary to put the reception circuit section in a standby operation state in order to be able to receive a signal at anytime. However, since the power consumption becomes large by doing so, the reception operation is designed to be performed discontinuously at every predetermined reception cycle.    [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2007-094719